docs: def get_convex_hull(self):
          """
          Get a convex polygon object that contains projections of all the points
          of the mesh.
  
          :returns:
              Instance of :class:`openquake.hazardlib.geo.polygon.Polygon` that
              is a convex hull around all the points in this mesh. If the
              original mesh had only one point, the resulting polygon has a
              square shape with a side length of 10 meters. If there were only
              two points, resulting polygon is a stripe 10 meters wide.
          """
          proj, polygon2d = self._get_proj_convex_hull()
          # if mesh had only one point, the convex hull is a point. if there
          # were two, it is a line string. we need to return a convex polygon
          # object, so extend that area-less geometries by some arbitrarily
          # small distance.
          if isinstance(polygon2d, (shapely.geometry.LineString,
                                    shapely.geometry.Point)):
              polygon2d = polygon2d.buffer(self.DIST_TOLERANCE, 1)
  
          # avoid circular imports
          from openquake.hazardlib.geo.polygon import Polygon
          return Polygon._from_2d(polygon2d, proj)